Telecommunications networks transmit voice and other data between end users. The networks include switch and management nodes for processing and routing traffic in the network and links between the nodes for carrying the traffic. The links are circuit switched or packet switched wireline links, wireless links, or a combination of link types. End users communicate data over telephones, computers, personal digital assistants (PDA) and other similar devices.
Telecommunication nodes include redundant equipment and are connected to redundant to provide fault tolerance and allow continued operation in the event of equipment or link failure. Typically, each transmission link as well as line or switch cards of the nodes are backed up by corresponding links and cards to ensure that all traffic is protected at all parts of the network. This 1+1 protection, however, is expensive to maintain as fully half of the networks capacity is maintained in reserved for protection switching and is not used during normal operation of the network.
To increase network efficiency, 1:N protection architectures have been developed and deployed in telecommunications nodes. In this architecture, a number (N) of cards or other items are protected by a single item. Thus full protection is provided for any single failure. Multiple concurrent failures, however, cannot be completely protected. In the event of multiple concurrent failures, equipment is typically protected based on a failure request priority. Within the priorities, equipment is protected on a first failed basis, which can lead to less important equipment being protected at the expense of later failing, more important equipment.